--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/wp/wp-includes/class-wp-block-pattern-categories-registry.php	Tue Dec 15 13:49:49 2020 +0100
@@ -0,0 +1,152 @@
+<?php
+/**
+ * Blocks API: WP_Block_Pattern_Categories_Registry class
+ *
+ * @package WordPress
+ * @subpackage Blocks
+ * @since 5.5.0
+ */
+
+/**
+ * Class used for interacting with block pattern categories.
+ */
+final class WP_Block_Pattern_Categories_Registry {
+	/**
+	 * Registered block pattern categories array.
+	 *
+	 * @var array
+	 */
+	private $registered_categories = array();
+
+	/**
+	 * Container for the main instance of the class.
+	 *
+	 * @var WP_Block_Pattern_Categories_Registry|null
+	 */
+	private static $instance = null;
+
+	/**
+	 * Registers a pattern category.
+	 *
+	 * @since 5.5.0
+	 *
+	 * @param string $category_name       Pattern category name.
+	 * @param array  $category_properties Array containing the properties of the category: label.
+	 * @return bool True if the pattern was registered with success and false otherwise.
+	 */
+	public function register( $category_name, $category_properties ) {
+		if ( ! isset( $category_name ) || ! is_string( $category_name ) ) {
+			_doing_it_wrong( __METHOD__, __( 'Block pattern category name must be a string.' ), '5.5.0' );
+			return false;
+		}
+
+		$this->registered_categories[ $category_name ] = array_merge(
+			array( 'name' => $category_name ),
+			$category_properties
+		);
+
+		return true;
+	}
+
+	/**
+	 * Unregisters a pattern category.
+	 *
+	 * @since 5.5.0
+	 *
+	 * @param string $category_name     Pattern name including namespace.
+	 * @return bool True if the pattern was unregistered with success and false otherwise.
+	 */
+	public function unregister( $category_name ) {
+		if ( ! $this->is_registered( $category_name ) ) {
+			/* translators: 1: Block pattern name. */
+			$message = sprintf( __( 'Block pattern category "%1$s" not found.' ), $category_name );
+			_doing_it_wrong( __METHOD__, $message, '5.5.0' );
+			return false;
+		}
+
+		unset( $this->registered_categories[ $category_name ] );
+
+		return true;
+	}
+
+	/**
+	 * Retrieves an array containing the properties of a registered pattern category.
+	 *
+	 * @since 5.5.0
+	 *
+	 * @param string $category_name Pattern category name.
+	 * @return array Registered pattern properties.
+	 */
+	public function get_registered( $category_name ) {
+		if ( ! $this->is_registered( $category_name ) ) {
+			return null;
+		}
+
+		return $this->registered_categories[ $category_name ];
+	}
+
+	/**
+	 * Retrieves all registered pattern categories.
+	 *
+	 * @since 5.5.0
+	 *
+	 * @return array Array of arrays containing the registered pattern categories properties.
+	 */
+	public function get_all_registered() {
+		return array_values( $this->registered_categories );
+	}
+
+	/**
+	 * Checks if a pattern category is registered.
+	 *
+	 * @since 5.5.0
+	 *
+	 * @param string $category_name       Pattern category name.
+	 * @return bool True if the pattern category is registered, false otherwise.
+	 */
+	public function is_registered( $category_name ) {
+		return isset( $this->registered_categories[ $category_name ] );
+	}
+
+	/**
+	 * Utility method to retrieve the main instance of the class.
+	 *
+	 * The instance will be created if it does not exist yet.
+	 *
+	 * @since 5.5.0
+	 *
+	 * @return WP_Block_Pattern_Categories_Registry The main instance.
+	 */
+	public static function get_instance() {
+		if ( null === self::$instance ) {
+			self::$instance = new self();
+		}
+
+		return self::$instance;
+	}
+}
+
+/**
+ * Registers a new pattern category.
+ *
+ * @since 5.5.0
+ *
+ * @param string $category_name       Pattern category name.
+ * @param array  $category_properties Array containing the properties of the category.
+ * @return bool True if the pattern category was registered with success and false otherwise.
+ */
+function register_block_pattern_category( $category_name, $category_properties ) {
+	return WP_Block_Pattern_Categories_Registry::get_instance()->register( $category_name, $category_properties );
+}
+
+/**
+ * Unregisters a pattern category.
+ *
+ * @since 5.5.0
+ *
+ * @param string $category_name       Pattern category name including namespace.
+ * @return bool True if the pattern category was unregistered with success and false otherwise.
+ */
+function unregister_block_pattern_category( $category_name ) {
+	return WP_Block_Pattern_Categories_Registry::get_instance()->unregister( $category_name );
+}